Passing Data Between View Controllers

Ios Objective C Swift Model View Controller Uiviewcontroller

Passing data between view controllers is a common requirement in iOS app development. It involves transferring data from one view controller to another, allowing the receiving view controller to access and use that data.

Method 1: Using a Segue

A common way to pass data between view controllers is by using segues. Segues define a transition between two view controllers in a storyboard. Here's how you can do it:

    1. Declare a property in the destination view controller to hold the data.
@interface DestinationViewController : UIViewController
@property (nonatomic, strong) NSString *dataToPass;
@end
    1. Implement the prepareForSegue:sender: method in the source view controller.
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
    if ([segue.identifier isEqualToString:@"mySegue"]) {
        DestinationViewController *destVC = segue.destinationViewController;
        destVC.dataToPass = @"Hello, World!";
    }
}
  1. In your storyboard, create a segue between the two view controllers and give it an identifier.

Method 2: Using a Delegate

Another way to pass data between view controllers is by using a delegate. A delegate is an object that acts on behalf of another object.

    1. Create a protocol in the source view controller specifying the methods that the delegate should implement.
@protocol DataPassDelegate <NSObject>
- (void)dataDidPass:(NSString *)data;
@end
    1. Declare a property in the source view controller to hold a delegate object.
@interface SourceViewController : UIViewController
@property (nonatomic, weak) id<DataPassDelegate> delegate;
@end
    1. In the source view controller, call the delegate method to pass the data.
if ([self.delegate respondsToSelector:@selector(dataDidPass:)]) {
    [self.delegate dataDidPass:@"Hello, World!"];
}
    1. In the destination view controller, implement the delegate method to receive the data.
- (void)dataDidPass:(NSString *)data {
    NSLog(@"%@", data);
}

Method 3: Using Singleton

A third approach to passing data between view controllers is by using a singleton. A singleton is a class that allows only one instance of itself to be created.

    1. Create a singleton class in which you can store and access the data.
@interface DataManager : NSObject
@property (nonatomic, strong) NSString *data;
+ (instancetype)sharedManager;
@end

@implementation DataManager
+ (instancetype)sharedManager {
    static DataManager *shared = nil;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        shared = [[self alloc] init];
    });
    return shared;
}
@end
    1. Set the data in the singleton class in the source view controller.
[[DataManager sharedManager] setData:@"Hello, World!"];
    1. Get the data from the singleton class in the destination view controller.
NSString *data = [[DataManager sharedManager] data];
NSLog(@"%@", data);

These are just a few methods to pass data between view controllers in iOS. Each method has its own advantages and use cases, so choose the one that best fits your app's needs.

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